import java.util.LinkedList;
import java.util.Queue;

public class Solution3 {
    public static void main(String[] args) {
    Solution3 s = new Solution3();
    int[][] grid = {{1,1,0,0,0},
                    {1,1,0,0,0},
                    {0,0,0,1,1},
                    {0,0,0,1,1}};
        System.out.println(s.maxAreaOfIsland(grid));
    }
    int m;
    int n;
    int[] dx = {0, 0, 1, -1};
    int[] dy = {1, -1, 0, 0};
    boolean[][] check;
    public int maxAreaOfIsland(int[][] grid) {
        m = grid.length;
        n = grid[0].length;
        check = new boolean[m][n];
        int ret = 0;

        Queue<int[]> q = new LinkedList<>();
        for(int i = 0; i < m; i++) {
            for(int j = 0; j < n; j++) {
                if(grid[i][j] == 1 && check[i][j] == false) {
                    q.add(new int[]{i, j});
                    check[i][j] = true;
                    int count = bfs(grid, q);
                    count++;
                    ret = Math.max(ret, count);
                }
            }
        }
        return ret;
    }

    public int bfs(int[][] grid, Queue<int[]> q) {
        int count = 0;
        while(!q.isEmpty()) {
            int[] t = q.poll();
            int a = t[0];
            int b = t[1];
            for(int k = 0; k < 4; k++) {
                int x = a + dx[k];
                int y = b + dy[k];
                if(x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == 1 && check[x][y] == false) {
                    q.add(new int[]{x, y});
                    check[x][y] = true;
                    count++;
                }
            }
        }
        return count;
    }
}
